This invention relates to manual-type transmissions and, more particularly, to manual-type transmissions employing planetary gearsets.
Automobiles generally employ one of two types of transmissions, either a manual-type transmission or an automatic shifting-type transmission. Manual-type transmissions include an input clutch, which is selectively engageable to connect a transmission input shaft with an engine output shaft. The transmission input shaft generally has a head gearset, which provides a step ratio between the input shaft and a countershaft, which has a plurality of gear members rotatably mounted thereon. An output shaft generally has another plurality of gears meshing with the gears in the countershaft to provide various ratios between the input shaft and the output shaft. Either the gear mechanisms on the countershaft or the gear mechanisms on the output shaft are interconnected with their respective shaft through mechanical clutches, commonly termed synchronizer clutches. The number of meshing pairs of gears is equal to the number of forward gears (assuming one of the forward gears is one to one) plus one idler gear for the reverse operation.
The synchronizer clutches are manipulated either through a manual linkage controlled by the operator or through a hydraulic or electrical actuator which is also manipulated by the operator.
It is an object of the present invention to provide an improved manual-type transmission employing two planetary gearsets.
In one aspect of the present invention, one of the planetary gearsets is interconnectible with the input shaft through a two-way synchronizer, which has an input portion selectively connectible with a power input shaft through a selectively engageable input clutch.
In another aspect of the present invention, a second selectively operable synchronizer clutch is connectible to provide two output members from the first planetary gearset individually.
In yet another aspect of the present invention, the second synchronizer clutch has an output member, which provides input drive to a third synchronizer clutch.
In still another aspect of the present invention, a third synchronizer clutch is selectively manipulable to three positions to establish three input drive paths to the second of the planetary gearsets.
In a yet still another aspect of the present invention, the second of the planetary gearsets has two members thereof selectively connectible with a transmission output shaft through a fourth selectively manipulable synchronizer clutch.
In a further aspect of the present invention, a fifth synchronizer clutch is operable to selectively connect two members of the second planetary gearset with a ground member, such as the transmission case.
In a yet further aspect of the present invention, the synchronizer clutches are manipulable in combinations to establish at least six forward speed ratios and one reverse speed ratio between the input shaft and the output shaft of the transmission.
The present invention incorporates two planetary gearsets, which are interconnected with each other through two selectively operable synchronizer clutches. One of the planetary gearsets is selectively connectible with a transmission input shaft through another synchronizer clutch. The second of the planetary gearsets is selectively connectible with a transmission output shaft through yet another synchronizer clutch. The second planetary gearset also incorporates a synchronizer clutch, which selectively connects two of the members of the second planetary gearset with a ground portion of the transmission.
The first of the planetary gearsets, in at least one embodiment of the present invention, is a simple planetary gearset and the second planetary gearset is a compound planetary gearset. In another embodiment of the present invention, the input planetary gearset is a compound planetary gearset and the output planetary gearset is a simple planetary gearset.